NXP Semiconductors K22F series, Reference Manual, Page: 52 / 1407

2.2.3 Memories and Memory Interfaces
The following memories and memory interfaces are available on this device.
Table 2-4. Memories and memory interfaces
Module Description
Flash memory • Program flash memory — non-volatile flash memory that can execute
program code
Flash memory controller Manages the interface between the device and the on-chip flash memory.
SRAM Internal system RAM. Partial SRAM kept powered in LLS2 and VLLS2 low leakage
mode.
System register file 32-byte register file that is accessible during all power modes and is powered by
VDD.
VBAT register file 32-byte register file that is accessible during all power modes and is powered by
VBAT.
Serial programming interface (EzPort) Same serial interface as, and subset of, the command set used by industry-
standard SPI flash memories. Provides the ability to read, erase, and program
flash memory and reset command to boot the system after flash programming.
FlexBus External bus interface with multiple independent, user-programmable chip-select
signals that can interface with external SRAM, PROM, EPROM, EEPROM, flash,
and other peripherals via 8-, 16- and 32-bit port sizes. Configurations include
multiplexed or non-multiplexed address and data buses using 8-bit, 16-bit, 32-bit,
and 16-byte line-sized transfers.
2.2.4 Clocks
The following clock modules are available on this device.
Table 2-5. Clock modules
Module Description
Multi-clock generator (MCG) The MCG provides several clock sources for the MCU that include:
• Phase-locked loop (PLL) — Voltage-controlled oscillator (VCO)
• Frequency-locked loop (FLL) — Digitally-controlled oscillator (DCO)
• Internal reference clocks — Can be used as a clock source for other on-chip
peripherals
48 MHz Internal Reference Clock
(IRC48M) The IRC48M provides an internally generated clock source. Clock Recovery
circuitry uses the incoming USB data stream to adjust the internal oscillator and
enables the internal oscillator to meet the requirements for USB clock tolerance.
System oscillator The system oscillator, in conjunction with an external crystal or resonator,
generates a reference clock for the MCU.
Real-time clock oscillator The RTC oscillator has an independent power supply and supports a 32 kHz
crystal oscillator to feed the RTC clock. Optionally, the RTC oscillator can replace
the system oscillator as the main oscillator source.
Module Functional Categories
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
52 NXP Semiconductors